You can pack your carry-on and show up ridiculously early to get through airport security, but it’s impossible to prepare for a flight delay. Even if you obsessively check the weather before heading to the airport, clear skies don't necessarily indicate a smooth trip. Data from the U.S. Department of Transportation shows that technical issues on the airline’s side are more likely to keep your plane grounded than severe storms, Money reports.

The department’s Bureau of Transportation Statistics found that problems caused by the airlines themselves accounted for more than 323,000 delays and about a third of total delay time last year. These problems include things like computer glitches, maintenance and mechanical problems, and scheduling issues with the crew. Inclement weather, on the other hand, like snowstorms and thunderstorms, could be blamed for just 5 percent of delay time and impacted about 36,000 flights.

While travelers may feel frustrated that the causes of so many delays are within the airline’s control, these numbers are actually a good sign. In the early 2000s, weather was the root of half of all delay time. Those rates have dropped significantly in the past two years, indicating that airlines are getting better at handling bad weather. Now if only airlines could manage the rest of their operations as well—then air travel might be a less stressful experience.

[h/t Money]

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